diff --git a/src/zm_crypt.cpp b/src/zm_crypt.cpp
index 5f4139b61..0a5b8996a 100644
--- a/src/zm_crypt.cpp
+++ b/src/zm_crypt.cpp
@@ -14,7 +14,7 @@
 
 // returns username if valid, "" if not
 #if HAVE_LIBJWT
-std::pair <std::string, unsigned int> verifyToken(std::string jwt_token_str, std::string key) {
+std::pair <std::string, unsigned int> verifyToken(const std::string &jwt_token_str, const std::string &key) {
   std::string username = "";
   unsigned int token_issued_at = 0;
   int err = 0;